The present invention relates to a method and system for determining the direction of fluid flow, such as fluid flow through pipelines or similar conduits for delivering natural gas, crude oil, and other liquid or gas energy commodities. The method and system relies on the measurement of acoustic frequencies generated by the fluid, thus allowing for determination of the direction of flow and/or identification of a change in the operational state of a component associated with the conduit without direct access to the fluid.
Natural gas, crude oil, and other similar liquid or gas energy commodities comprise a multi-billion dollar economic market. These commodities are bought and sold by many parties, and as with any traded market, information about the traded commodities is very valuable to market participants. Specifically, the operations of the various components and facilities of the production, transportation, storage, and distribution systems for each of these commodities can have significant impacts on the price and availability of these commodities, making information about said operations valuable. Furthermore, such information generally is not disclosed publicly by the various component owners or operators, and access to said information is therefore limited.
In co-pending and commonly assigned U.S. patent application Ser. No. 10/967,737 filed Oct. 18, 2004, which has been incorporated herein by reference, a method and system for monitoring fluid flow is described that relies on the measurement of acoustic waves generated by the fluid from a location external to the conduit in which the fluid is flowing, thus allowing for monitoring of the flow rate without direct access to the fluid. Furthermore, U.S. patent application Ser. No. 10/967,737 describes how to estimate the operational dynamics of components or facilities of the production, transportation, storage, and distribution systems for the energy commodities through such measurement of acoustic waves.
In general, fluids (whether compressible or incompressible) flowing through pipelines or similar conduits produce acoustic waves, i.e., sound or vibration. The sound produced by the flow of natural gas or other energy commodity can be characterized by its amplitude and frequency. In this regard, the amplitude and frequency are generally directly related to the velocity of the fluid through the conduit, along with the associated operational components (e.g., valves, compressors, and meters), and thus the flow rate of the fluid. Therefore, a sound transducer or similar sensor can be positioned to detect the acoustic waves emanating from a particular conduit caused by fluid flow through that conduit, and by recording and analyzing the acoustic waves, the flow rate through the conduit can be estimated. In this regard, the flow rate is commonly expressed as a volumetric flow rate, i.e., characterized as the volume of fluid passing by a designated point over a predetermined time period.
Therefore, according to the teachings of U.S. patent application Ser. No. 10/967,737, one or more sound transducers are positioned in proximity to a pipeline such that acoustic waves can be reliably detected. Each sound transducer detects the amplitude and/or frequency of the acoustic waves generated by the gas flow through the pipeline and generates a signal representative of that measurement. The signal generated by each sound transducer is transmitted to an above-ground monitoring device in general proximity to the sound transducers and the monitored pipeline. The monitoring device houses the various electronic equipment necessary to process the signals from the sound transducers and transmit collected data to a central processing facility. Specifically, the monitoring device is programmed such that it periodically or continuously collects data from the sound transducers, processes that data into a form suitable for transmission, and transmits the data to a remote central processing facility.
At the central processing facility, a computational analysis is performed by a digital computer program to determine the flow rate of the fluid through the monitored pipeline. Furthermore, for any particular facility or other component of the production, transportation, storage, and/or distribution system for which all, or most of, the connected pipelines are monitored, through a simple summing of the volumetric flow rates on each pipeline, the output or production of the facility can be determined. Then, information associated with the production or output of one or more facilities or components can be communicated to third parties. This information may include not only the measured flow rates or output estimates, but also historical data, capacity estimates, or similar data that places the measured flow rates or output estimates in context for market participants and other interested parties.
In some circumstances, mere knowledge of the direction of flow has value. For example, natural gas is located and collected by production companies from geographically dispersed wells. The natural gas collected from these wells is delivered through a network of pipelines (or similar conduits) and then delivered to storage facilities. Knowledge of whether natural gas is being injected into a storage facility or withdrawn from a facility can be very important to those involved in trading natural gas commodities, as the operational state of a storage facility is an indicator of the demand for natural gas.